call a good liquor store near you and see what they offer. several liquor stores around my area carry the stout in half barrels...
LOL there's only one liquor store allowed here in Finland. Although Guinness stout's alcohol percentage is low enough to fit into the 3rd taxing class available at any grocery store I doubt any one of them would sell those half barrels to an individual. Their markets are for restaurants and pubs selling beverages by the pint, sold by specified restaurant suppliers.
As for more about the subject, a fellow once had a watercooling system, the reservoir of which was a baby's potty... The liquid might have been yellow, if I recall correctly.